It is known to provide fin strips in heat exchangers to improve the heat transfer characteristics of the heat exchangers by providing additional heat conductive paths through periodic contact points with the walls of the heat exchange units or tubes of the heat exchangers. Fin strips may be provided on either the external side or the internal side, or both, of the heat exchange units or tubes of the heat exchanger. One common type of fin strips, sometimes referred to as turbulators, are provided inside the heat exchange units or tubes of heat exchangers to improve heat transfer characteristics of the heat exchangers. In general, such fin strips cause the fluid flowing through the heat exchange units to flow in a turbulent manner, thereby further enhancing the heat transfer characteristics of the heat exchanger. Examples of some fin strips are shown in U.S. Pat. Nos. 3,732,921 to Hillicki, et al.; 3,743,011 to Frost; 3,734,135 to Mosier; 3,763,930 to Frost; 4,360,055 to Frost; 4,561,494 to Frost; 4,967,835 to Lefeber, and 5,078,209 to Kerkman, et al.
Roll forming is one method commonly used to produce fin strips. Typically, a length of sheet stock having an initial width is run through a roll forming machine to provide a fin strip having a desired width. The sheet stock can either be purchased on the open market pre-slit to the initial width, or can be purchased at a wider width and slit by the fin strip manufacturer to the initial width in a slitting station prior to the forming stations. This approach requires either: a) that a single strip of sheet stock be run through the roll forming machine at a time, which tends to limit the output of the roll forming machine; or b) that multiple ribbons of sheet stock are run in parallel through the roll forming machine, which increases the output of the roll forming machine, but requires extensive set-up time as each of the individual strips are threaded through the roll forming stations.